typed for preventing a repeat of the tragedy

src/compiler/compile/render_dom/wrappers/Element/Attribute.ts

@@ -9,7 +9,7 @@ import Text from '../../../nodes/Text';
 import handle_select_value_binding from './handle_select_value_binding';
 import { Identifier, Node } from 'estree';
 import { namespaces } from '../../../../utils/namespaces';
-import { boolean_attributes } from '../../../../../shared/boolean_attributes';
+import { BooleanAttributes, boolean_attributes } from '../../../../../shared/boolean_attributes';
 import { regex_double_quotes } from '../../../../utils/patterns';
 
 const non_textlike_input_types = new Set([
@@ -324,7 +324,8 @@ export default class AttributeWrapper extends BaseAttributeWrapper {
 }
 
 // source: https://html.spec.whatwg.org/multipage/indices.html
-const attribute_lookup = {
+type AttributeMetadata = { property_name?: string, applies_to?: string[] };
+const attribute_lookup: { [key in BooleanAttributes]: AttributeMetadata } & { [key in string]: AttributeMetadata } = {
 	allowfullscreen: { property_name: 'allowFullscreen', applies_to: ['iframe'] },
 	allowpaymentrequest: { property_name: 'allowPaymentRequest', applies_to: ['iframe'] },
 	async: { applies_to: ['script'] },
@@ -351,6 +352,7 @@ const attribute_lookup = {
 	indeterminate: { applies_to: ['input'] },
 	inert: {},
 	ismap: { property_name: 'isMap', applies_to: ['img'] },
+	itemscope: {},
 	loop: { applies_to: ['audio', 'bgsound', 'video'] },
 	multiple: { applies_to: ['input', 'select'] },
 	muted: { applies_to: ['audio', 'video'] },

src/shared/boolean_attributes.ts

@@ -1,5 +1,5 @@
 // source: https://html.spec.whatwg.org/multipage/indices.html
-export const boolean_attributes = new Set([
+const _boolean_attributes = [
 	'allowfullscreen',
 	'allowpaymentrequest',
 	'async',
@@ -12,6 +12,7 @@ export const boolean_attributes = new Set([
 	'disabled',
 	'formnovalidate',
 	'hidden',
+	'indeterminate',
 	'inert',
 	'ismap',
 	'itemscope',
@@ -26,4 +27,7 @@ export const boolean_attributes = new Set([
 	'required',
 	'reversed',
 	'selected'
-]);
+] as const;
+
+export type BooleanAttributes = typeof _boolean_attributes[number];
+export const boolean_attributes: Set<string> = new Set([..._boolean_attributes]);